A large and growing population of users is enjoying entertainment through the consumption of digital media, such as music, movies, images, electronic books, and so on. The users employ various electronic devices to consume such media. Among these electronic devices (referred to herein as “user equipment” or “UEs”) are electronic book readers, cellular telephones, personal digital assistants (PDAs), portable media players, tablet computers, netbooks, laptops, and the like. Providing a wide and increasing variety of applications and services, these electronic devices each include at least one antenna to support wireless communications with a communications infrastructure.
Mobile devices may include antennae capable of communication across multiple frequency bands. A single “multi-band” antenna may support communications on multiple frequency bands. In legacy “third generation” (3G) devices, multi-band antenna may support two distinct ranges of frequencies, providing one resonant mode in a lower frequency band and one resonant mode in a higher frequency band. Application services offered by 3G devices include voice telephony, mobile Internet access, video calls and mobile TV. Some of these services may be supported on some of the frequency bands available to the device but not on others.
“Long Term Evolution” (LTE) (sometimes marketed as “4G LTE”) is a communication standard bridging between legacy 3G communications and higher-speed “fourth generation” (4G) services. “LTE Advanced” (LTE-A) is an enhancement of LTE and supports “True 4G” communications. Both LTE and LTE-A have been standardized by the 3rd Generation Partnership Project (3GPP). In general, increasing the data rate provided to the services over that offered by 3G requires increasing the bandwidth available to the service. The performance of the higher speed services offered by 4G/LTE may be hampered by the limited ability to operate in available bands and the relative narrowness of the range of frequencies readily accessible within a band as afforded by conventional multi-band antennae that were used with 3G.
Past solutions to expand the bandwidth available to 4G devices have resulted in increasing the size of multi-band antennae, such as adding active tuning elements to extend bandwidth, or using separate antennae to achieve cover additional frequency bands. In view of the limited physical space available in mobile devices such as cellular telephones and tablet computers, the need to optimize space utilization, and the general trend for devices to get smaller—rather than larger—with each generation, increasing the space dedicated to antennae necessitates design trade-offs (e.g., reducing the size of the battery) that may result in improving one feature at the expense of another.